.\" -*- nroff -*-
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" Copyright (c) 2011 Cisco Systems, Inc.  All rights reserved.
.\" $COPYRIGHT$
.TH MPI_Waitall 3 "Jun 10, 2020" "4.0.4" "Open MPI"
.SH NAME
\fBMPI_Waitall\fP \- Waits for all given communications to complete.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Waitall(int \fIcount\fP, MPI_Request\fI array_of_requests[]\fP,
	MPI_Status \fI*array_of_statuses\fP)

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
count
Lists length (integer).
.TP 1i
array_of_requests
Array of requests (array of handles).
.sp
.SH OUTPUT PARAMETERS
.ft R
.TP 1i
array_of_statuses
Array of status objects (array of status).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
Blocks until all communication operations associated with active handles in the list complete, and returns the status of all these operations (this includes the case where no handle in the list is active). Both arrays have the same number of valid entries. The ith entry in array_of_statuses is set to the return status of the ith operation. Requests that were created by nonblocking communication operations are deallocated, and the corresponding handles in the array are set to MPI_REQUEST_NULL. The list may contain null or inactive handles. The call sets to empty the status of each such entry.
.sp
The error-free execution of MPI_Waitall(count, array_of_requests, array_of_statuses) has the same effect as the execution of  MPI_Wait(&array_of_request[i], &array_of_statuses[i]), for i=0,...,count-1, in some arbitrary order. MPI_Waitall with an array of length 1 is equivalent to MPI_Wait.
.sp
When one or more of the communications completed by a call to MPI_Waitall fail, it is desirable to return specific information on each communication. The function MPI_Waitall will return in such case the error code MPI_ERR_IN_STATUS and will set the error field of each status to a specific error code. This code will be MPI_SUCCESS if the specific communication completed; it will be another specific error code if it failed; or it can be MPI_ERR_PENDING if it has neither failed nor completed. The function MPI_Waitall will return MPI_SUCCESS if no request had an error, or will return another error code if it failed for other reasons (such as invalid arguments). In such cases, it will not update the error fields of the statuses.
.sp
If your application does not need to examine the \fIarray_of_statuses\fP field, you can save resources by using the predefined constant MPI_STATUSES_IGNORE can be used as a special value for the \fIarray_of_statuses\fP argument.

.SH ERRORS
For each invocation of MPI_Waitall, if one or more requests generate
an MPI exception, only the \fIfirst\fP MPI request that caused an
exception will be passed to its corresponding error handler.  No other
error handlers will be invoked (even if multiple requests generated
exceptions).  However, \fIall\fP requests that generate an exception
will have a relevant error code set in the corresponding
status.MPI_ERROR field (unless MPI_STATUSES_IGNORE was used).
.sp
The default error handler aborts the MPI job, except for I/O function
errors. The error handler may be changed with MPI_Comm_set_errhandler,
MPI_File_set_errhandler, or MPI_Win_set_errhandler (depending on the
type of MPI handle that generated the MPI request); the predefined
error handler MPI_ERRORS_RETURN may be used to cause error values to
be returned. Note that MPI does not guarantee that an MPI program can
continue past an error.
.sp
If the invoked error handler allows MPI_Waitall to return to the
caller, the value MPI_ERR_IN_STATUS will be returned in the C and
Fortran bindings.  In C++, if the predefined error handler
MPI::ERRORS_THROW_EXCEPTIONS is used, the value MPI::ERR_IN_STATUS
will be contained in the MPI::Exception object.  The MPI_ERROR field
can then be examined in the array of returned statuses to determine
exactly which request(s) generated an exception.

.SH SEE ALSO
.ft R
.sp
MPI_Comm_set_errhandler
.br
MPI_File_set_errhandler
.br
MPI_Test
.br
MPI_Testall
.br
MPI_Testany
.br
MPI_Testsome
.br
MPI_Wait
.br
MPI_Waitany
.br
MPI_Waitsome
.br
MPI_Win_set_errhandler
.br

